Toggle drawing press



June 10, 1930. w. KLOCKE TOGGLE DRAWING PRESS Filed June 14, 1928 3 Sheets-Sheet l INVENTOR June 10, 1930. w. KLOCKE TOGGLE DRAWING PRESS Filed June A, 1928 3 Sheets-Sheet 2 INVENTbR MW WMJ By Attorneys, I

June 10, 1930. w. KLOCKE TOGGLE DRAWING PRESS Filed June 14. 1928 3 Sheets-Sheet 3 INVENTOR zflfiwm By Attorney s, Sh wn/ W l Patented June 10, 1930 lJNiTED STATES PATENT OFFICE WILLIAM KLOCKE, F WOODHAVEN, NEW YORK. ASSIGNOR TO E. W. BLISS COMPANY,

OF BROOKLYN, NEW YORK, A

CORPORATION OF DELAWARE TOGGLE DRAWING PRESS Application filed .Tune 14,

This invention relates to drawing presses or other presses for performing analogous operations, in which the blank-holder or similar clamping element is caused to engage the sheet-metal or other work under operation with a prolonged dwell, due to the concurrent action of multiple toggle devices following generally the mode of operation introduced by the Leavitt Patent No. 888,698, granted August 28, 1888. Another example of such press is found in my Patent No. 955,173, granted April 19, 1910. In such presses the crank-shaft, having a crank or cranks for operating the punch slide, has also a crank (preferably carried on a gear on its end) having a suitable angular lead over the punch crank and connected to drive a slide or other moving part which in turn is connected by toggle links to crank arms on rock-shafts on which are toggle arms connected by toggle links to the blank-holder slide; the arrangement being such that as the blank-holder operating crank passes its dead center, the links connecting the slide operated by this crank pass to opposite sides of their dead centers and thereby impart a greatly diminished angular movement to the rockshafts when the blank-holding toggles are straightened, so that these toggles are held substantially straight (being brought to a minute angle across their alignment axis, the effective length of the blank-holding toggles during this movement being varied to an amount which should be within the elastic limit of the metallic connections), whereby to impart to the blank-holder slide a prolonged and suiiicient-ly level dwell in the blank holding position.

Efforts have been made in presses operating on this principle to impart the desirable dwell to the blank-holding toggles in their position of alignment by other means than the superposing of the toggle dwells of multiple serially-acting toggles; thus, various arrangements of cams have been proposed, an example of which has been shown in the Leavitt Patent No. 151,224, granted April 28, 1891; but these have proven less desir- 1928. Serial No. 285,488.

able because of the wear engendered along the cam faces and roller.

The present invention provides an improved construction of such multiple toggle presses wherein a sufiiciently prolonged dwell is secured while holding the blankholding toggles stationary in their blankholding position, so as to give a level or positive dwell; and to accomplish this by a toggle action alone without any resort to cams.

To this end, in a press in which the toggle rock-shafts (or equivalent rocking elements) are operated through link connections with 6r a reciprocating slide, this slide, instead of being reciprocated by direct connection to a crank on or connected to the main or crank shaft, is operated therefrom through the intermediary of a rocking part in the nature of an elbow lever having two pivotal points, the one connecting by a link to the actuating crank, and the other connecting through a link to the said slide; the latter connection being in the nature of a toggle, in that the center lines between the respective axes move into alignment in the aligned or blank-holding position of the blank-holding toggles, crossing and re-crossing this aligned position during the period of dwell.

The result of this construction is that while the actuating crank is passing through a considerable are (approximately 90 degrees) its vertical movement in this arc, which heretofore has been communicated directly to the actuating slide, is resolved into a nearly horizontal movement of the second ary arm ofthe elbow lever, which diminishes the vertical movement of the actuating slide in the blank-holding position to nearly zero, and thus reduces the angular movement imparted by the links connecting this slide to the rock-shaft arms.

The accompanying drawings show a drawing press constructed in accordance with the present invention.

Figure 1 is a side elevation of the press.

Fig. 2 is a diagram plotting the movements of the blank-holding mechanism in the several operative positions.

Fig. 3 is a diagrammatic elevation showing a modified construction.

Fig. 1 is a side elevation corresponding to Fig. 1 and showing a modified construction of press.

Fig. 5 is a half front elevation of the press shown in Fig. a.

The press is not shown in front elevation because so viewed it does not differ in any essential respect from the construction shown in my said Patent No. 955,178, Fig. 1 of which shows the press in front elevation. The only difference is in the rockshaft operating slide (lettered h, 7i, in that patent), as to which the construction now preferred is sufliciently shown in the annexed drawings.

Referring to the drawings, A will designate the base of the press, and B one of its end frames; C is the main shaft or crankshaft having a crank or cranks which operate the punch slide (not shown) and usually provided with gear wheels on its opposite ends, one of which is shown at D. The blank-holder slide E is connected (through adjusting means a) with a crosshead 6 which affords a pivotal connection for the blank-holder operating toggles. These toggles are operated by rock-shafts F F on the front and rear of the press, which shafts have toggle arms 0 which connect by toggle links (Z with the crosshead b the arms 0 and links (Z thus constitute the blank-holder operating toggles. The rockshafts F have arms 6 connected by links f to an actuating slide G which, as heretofore, is driven from a crank stud H which conveniently is mounted on the outer side of each of the gears D, and has the usual angular lead over the punch-operating cranks, all as well understood. Heretofore the slide G has been extended downwardly,

and a link connection has been made directly to it from the crank stud H; this construction is changed by the present invention,

which substitutes an intervening rocker or elbow lever J pivoted at g on a pedestal h or other stationary part of the press frame, and having two joint studs, one of which, Z, is connected by a link or connecting rod with the crank stud H, and the other, 70, of which, is connected by a link or connecting rod Z with a pivot m on the slide -G.

The angular relation of the pivotal centers of 2' and with respect to the rocking pivot g of the rocker arm J is important. In the position shown in Fig. 1, where the blank-holding toggles 0, (Z, are straightened, the axis of the pivotal stud 7c is nearly in line between the rocker axis 9 and the pivot connection mwith the slide G. In this sameposition the joint axis 2' is located at one side, its preferable angular relation being such that when the crank H is at mid stroke, the axis of stud 2' will project horizontally from the pivotal axis 9; although this exact angular relation is not essential. The important relation is that in the upper position of the slide G, where the links f f stand horizontal, the axis of 6 shall be nearly in alignment with the center of the link Z, and this position of substantial alignment shall continue while the crank stud h is swinging across its dead center (in this case its upper dead center).

The effect of this construction and arrangement is most apparent from the diagram Fig. 2. In this diagram only the critical positions of the centers, and their arcs of travel, and the center lines of the connecting links and arms, are shown. There are shown in full lines the upper dead center position of crank H, the orbit of which is indicated by circle 10, the center line of link j, the center of coupling pin 2', the rocker center of axis 9, the axis of coupling pin 70, the center line of link Z, and the center lines of one link f, one rock-shaft arm @,.the rock-shaft F, and the toggle arm 0 and link (Z. As the shaft C revolves, the crank center H moves in circle 10 from position 11 through 12 to 13; in positions 11 and 13 the axis 2' is displaced to 14, thereby displacing axis is to point 15. The further rotation of the crank H to its lower dead center 16 swings the axis 71 down to point 17, and this angular movement of the rocker or elbow lever J carries the axis 70 down to point 18. In such a diagram the movement of the slide G can only be shown by a straight line representing the vertical translation of the center of pivotal axis m; and this, as the diagram shows only one-half of the toggle movement, is for convenience put in the same vertical line as the axis a, where the slide G is pivoted to'the link this vertical line is shown at 0.

In the lowest position of the crank stud H at 16 the center on has been lowered to 19 and the center a to 20; thus the link 7 is drawn down to a nearly vertical position, as shown by broken line 7, and the rockshaft arm 6 is down in position 6', the blankholding toggle arm and link being respectively in the positions shown at c and (Z, so that the blank-holder slide is lifted to its uppermost position. This position coincides substantially with that resulting from the construction heretofore used.

As the crank stud H moves from 16 upward to either 11 or 18 (according to the direction of rotation of the crank-shaft), the link is carried to position 21 or 22, and in either case the center 2' of rocker J is lifted to point 14 and the center Z0 is carried to point 15. This movement results in the straightening of the toggles, since the slide G is lifted so that the link 7 moves from its position 7" to the position shown in full lines, with the corresponding movements of the parts e, 0, (Z, to their full line position.

During the further movement of the crank stud H through the are 11, 12, 13, the pivotal center of the rocker J is carried from 15 to 15 and back to 15. During this movement the link Z is carried across its position of alignment between the centers 9 and 'm and back again. This movement, however, results in an extremely minute rising and falling movement 01: the slide G, and consequently of the centers m, a. This is due to the fact that the are 15-15 is described in such position that its chord is horizontal and the arc is of such proportion that its rise when intersecting the position of alignment is very short. During this movement from 15 to 15 and back, the pivotal center it executes a movement which is correspondingly small, and the link 7 changes it angular position very slightly from a horizontal line or one at right angles to the crank arm 6. The arrangement has the highly advantageous result that the movement of the crank arm 6, and conse quently of the toggle members 0, (Z, in the aligned position of the toggle, becomes infinitesimal.

This result is attained more perfectly by the present invention than by any of the various toggle arrangements heretofore proposed. To illustrate this, it may be stated that in a press of the proportions shown in Figs. 1 and 2, the crank stud H traveling in a radius of 13 inches, and the toggle arms 0 having an effective length of 17 inches, the vertical movement of the slide, and consequently of the pivotal center a, corresponding to the arc movement 15 to 15',.is only 0.199 inch, and the movement of the toggle center 23, where c and (Z are jointed together, is reduced to 0.00052 inch; and the vertical movement of the lower end of the toggle during this same period is dimished to 1/35,000,000 inch, which obviously is so infinitestimal as to amount to an absolutely dead dwell. This is a result achieved in no prior form of double toggle press.

A modified construction is shown in Fig. :3, in which the rocker J, here letterd J,

or different form and arrangement, but has essentially the same operation. The operation is in a sense inverted, in that the are traversed by the actuating crank H corresponding to the period of dwell, instead of being at the upper throw of the crank, as indicated at 11, 12, 13, in Fig. 2, is at the lower throw of the crank, as indicated by 11, 12, 18, in Fig. 8. The rocker or elbow lever J has two arms, the lower one carrying a pivotal stud a" corresponding to the stud z in Fig. 2, and the upper one carrying a pivotal stud k corresponding to the stud 7c in Fig. 2. lVith this explanation the operation will be obvious.

Thus far the invention has been described with reference to toggle presses having rockshaits extending from right to left across the front and rear of the press in accordance with the patents hereinbe'fore referred to. The invention, however, is applicable to an other standard type oi toggle drawing press in which the rock-shafts or equivalent rocking parts are located at opposite ends of the press and extend from tront to rear, or in planes parallel with those occupied by the side frames of the press. An example of such arrangement is shown in my Patent No. 1,435,532, granted November 14:, 1922. Another example is shown in my Patent No. 1,458,709, granted June 12, 1923. In those patents, as in the ones first herein referred to, the actuating crank on the main shaft gear is directly connected to reciprocate a vertical slide, and the movements of this slide actuate the adjacent toggle rock-shaft or equivalent rocking part. According to the present invention, the rocker J of Figs. 1 and 2, or some equivalent form of such rocker, is interposed to modit y the movement transmitted from the actuating crank or crank stud H, to the same effect as in the form or press already described.

An example of such construction is shown in Figs. 1 and 5, wherein parts identical with those already described are designated by the same letters, and parts corresponding to, but specifically different from, those already described, are designated F, G 0 (Z etc. The parts F are either rock-shafts extending through from front to rear, or are fixed studs on which turn the levers formed of the respective arms 0 6 The links f, instead of being mounted to turn in a plane identical with or parallel with that or the slide G, as in Fig. 1, are turned at right angles thereto. The stress on the pivots n is resisted by tie-rods The function of the parts is performed in the same manner in the construction first described.

It will be perceived that my invention introduces essentially three successive pairs oi? toggles between the actuating crank stud and the blank-holder slide; of these, the first is the usual pair of toggles 0, (Z for immediately operating the blank-holder; the second is constituted by the links 7 f in cooperation with the slide G, and with the operating rocker arms 6; the third is constituted by the link Z and so much of the rocker J as includes its stud or pivotal center it, and the radius thence to the oscillating center 9. The movement being transmitted successively or serially through these three toggle connections, practically cxtinguishes all movement in the final or blankholder operating toggles during the period of dwell.

It will be obvious that my invention may be otherwise modified to adapt it to any existing type or arrangement of multiple toggle presses.

What I claim is:

1. In press having a main shaft, an actuating crank thereon, a blank-holder, toggles for operating the blank-holder, rock-shafts operating said toggles, and an arm on each said rock-shaft, extending in line with the toggles when the latter are straightened, an operating part and links therefrom to said arms, said links being at right angles to said arms in the straighten ed positicnrof the toggles, the combination therewith of a rocker part having a link connection with said crank, and a link connection with said operating part, the rocker having its pivot for said latter connection a ranged on a radius which in the straightened position of said toggles is aligned with its connecting link to impart a minimum movement to said toggles in their approximately straightened position.

2. In a press having a main shaft, an actuating crank thereon, a blank-holder, toggles for operating the blank-holder, rock-shafts operating said toggles, each said shaft having an arm, an operating part, and links connecting said arms to said operating part, said links arranged at right angles to said arms when the toggles are straightened, the combination therewith of a rocker part having in effect two radial arms at different angles, a link connection between one such arm and said crank, and a link connection between the other arm and said operating part, the rocker having its pivot for said latter connection arranged on a radius which in the straightened posi tion of said toggles is aligned with its connecting link to impart a minimum movement to said toggles in their approximately straightened position.

3. In a press having a main shaft, a blank-holder, toggles for operating the blank-holder, rock-shafts operating said toggles, an operating slide, link connections from said slide to operate said rock-shafts, and an actuating crank on said main shaft, the combination therewith of a rocker part having a link connection with said crank and a link connection with said slide, the latter connection arranged with its pivotal center on a radius aligned with its connecting link when the blank-holder operating toggles are in their straightened position, and the former connection arranged with its pivotal center on a radius out of alignment with its connecting link in such position.

4. A press having a main shaft with an actuating c*ank thereon, a blank-holder, toggles for operating the blank-holder, rock-shafts operating said toggles, each rock-shaft having an arm extending in line with the toggles when the latter are strz-tightened, a vertically-movable slide between the rock-shafts, links connecting said arms with said. slide, said links being at right angles to said arms in the straightened position of the toggles, andmeans for reciprocating said slide from said main shaft, comprising a rocker part having in effect two radial arms at different angles, a link connecting one such arm to the slide, the rocker pivot for such link connection being arranged on a radius which in the straightened position of said toggles is aligned with such link, and a link connection between the other arm of said rocker part and said actuating crank, the pivot for said latter connection arranged at such angle from said other pivot. that its arc movement during the rotation of said crank lies wh lly to one side of an alignment be tween the lFOClIQl arm and connecting link.

In witness whereof, I have hereunto signed my name.

WILLIAM KLOCKE; 

